LPBRK – Loop break

Block SymbolLicensing group: STANDARD

Function Description
The LPBRK block is an auxiliary block often used in the control schemes consisting of the REXYGEN system function blocks. The block is usually placed in all feedback loops in the scheme. Its behaviour differs in the REXYGEN system and the Simulink system.

The LPBRK block creates a one-sample delay in the Simulink system. If there exists a feedback loop without the LPBRK block, the Simulink system detects an algebraic loop and issues a warning (Matlab version 6.1 and above). The simulation fails after some time.

The REXYGEN Compiler omits the LPBRK block, the only effect of this block is the breaking of the feedback loop at the block’s position. If there exists a loop without the LPBRK block, the REXYGEN Compiler compiler issues a warning and breaks the loop at an automatically determined position. It is recommended to use the LPBRK block in all loops to achieve the maximum compatibility between the REXYGEN system and the Simulink system.

Note: Behaviour of the LPBRK block has been changed since the version 3.0. The block is not removed by the REXYGEN Compiler but is present in the algorithm and clears the quality flag of the y output. This change is useful and necessary due to the quality propagation in function blocks. Original behaviour (e.g. the block is removed from the algorithm) can be forced by the RB = on parameter. The main function of the block (indication of the feedback signal) remains unchanged in all cases.

This block propagates the signal quality. More information can be found in the 1.4 section.

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